The research literature on workplace inequality has given comparatively little attention to age discrimination and its social-psychological consequences. In this article, we highlight useful insights from critical gerontological, labor process, and mental health literatures and analyze the patterning of workplace age discrimination and its implications for sense of job insecurity, job-specific stress, and the overall mental health of full-time workers 40 years old and above, covered by the Age Discrimination in Employment Act (ADEA). Our analyses, which draw on two decades and five waves of the General Social Survey (2002–2018), reveal (1) the prevalence of self-reported workplace age discrimination and growing vulnerability particularly for those 60 years and above, (2) clear social-psychological costs when it comes to job insecurity, work-specific stress, and overall self-reported mental health, and (3) dimensions of status and workplace social relations that offer a protective buffer or exacerbate age discrimination’s corrosive effects. Future research on age as an important status vulnerability within the domain of employment and the implications of unjust treatment for well-being and mental health are clearly warranted.